Battery charge problem.

[Scott58]

Hi everyone,

I have had my Scott Genius ebike for 2 years & recently had a problem with the battery not charging, I has a Bosch CX motor & a 36 volt 500 Wh battery I contacted the shop that sold me my bike & after explaining my problem they told me to drop it off so they could have a look. Before I took it to the shop I made sure the charger was working & advised them of this. The technician did diagnostic checks on the system & spoke to Bosch who after a while decided to replace the battery with a new one which charges find now. On collecting my bike the shop owner also gave me the old battery. I would like to see if I can find the problem with this old battery & keep it as a spare because it has only had light use, probably been charged 60 times. I am going to open it up to see if there's anything obviously wrong but would like to know if anyone can give me any tips on what to look for & test.

 

[AHicks]

Myself, I would do some poking around with a voltmeter. If the pack is intact internally (no blown fuses, switches OK, wiring not broken/ disconnected anywhere) I would start taking readings on the individual cells. There is very likely at least one that will be much lower than the rest. That cell will need to be replaced with an identical cell.

 

[Scott58]

Thanks AHicks, got a voltmeter so i should be ok with checking / replacing the cells if needed. Read recently about BMS controllers, the article made them sound technical, not sure if my battery has one but should find out when i open it up. Thanks again.

 

[Scott58]

Hi everyone,

Opened my Bosch powerpack 500 battery up yesterday, tested cells and all read the same. I think it must be the BMS because when i first had this problem it wouldn't charge correctly, (Intermittent charging) that's why i made sure the charger was working first. I Understand from reading articles the BMS controls the charge rate as well as balancing the charge in each cell but could do with speaking to someone with first hand knowledge.

 

[AHicks]

Let's back up a bit. Why did you think the battery wasn't charging?

 

[Scott58]

I came back from a ride having used about 40-50% of charge, 3 green lights out of 5 still on. I connected battery to charger and left it to charge. the next day i checked it and it still had 3 light on, i checked that power was going through the charger, plugged back in but still no change.

 

[LoganK]

Unfortunately, I don't have anything productive to add, but I am seeing the exact same behavior with my Bosch Powerpack: 3 lights out of 5, refuses to charge after a little more than 2 years. The battery refused to even power up the display when swapped into another bike.

Scott58, did you ever make progress? I'm tempted to start poking around, but I'm waiting until I hear back from the manufacturer on the battery warranty.

 

[AHicks]

A quick check with nothing fancier than a voltmeter set to measure DC voltage, might be to measure the voltage of the battery, and compare that to the voltage coming from/available at the charger's output wire. With a partially discharged battery, I would think you would see at least a couple of volts difference between the 2. If the charger voltage is higher, it should charge the battery.

 

[JRA]

There is the possibility that the onboard lights will show charge but the wire from the cells to the final output wire may have a connector that is not making good contact. You will have to undo the case screws and expose the inside to see.

 

[LoganK]

It's not quite as simple as hooking up a voltmeter and measuring the voltage because there is some sort of protocol to negotiate full power. It's probably not difficult to figure out, but it's definitely a challenge when I have only one battery that doesn't work.

JRA, there is a good chance you are correct. I have had intermittent power failures for the last year, usually resulting a jolt like dropping off a curb. I thought there might have been a wiring issue with the bike, but it's just as plausible that the loose connection is in the battery.

 

[AHicks]

My bike did that once. Battery power shut down completely after hitting a particularly jarring pot hole. It's never done it before or since, but I don't think the bike has been subjected to a jar quite like that before or since. I dismounted, wheeled the bike to the side of the road, hit the "on" button, the bike powered up, and we motored on down the road. Still not sure what to make of that incident. Everything still capable of creating full motor power (20+amps), so I doubt it's a bad connection anywhere. Is there an inertia switch somewhere? Dunno....